Basically, any slow song will work. After my pastor is done preaching I just do something like this. These chords work best with piano layered with strings.
Key of Eb LH/RH *means hold previous note(s)
Play slowly w/feeling:
Eb / G-Bb-Eb
* / Bb-Db-Eb
* / A-C-Eb
* / F-Ab-B-Eb
* / F-G-Bb-Eb
Eb / Db-Eb-Bb
* / C-Eb-F-A
* / B-Eb-F-Ab
* / Bb-Eb-F-G
(you can also use these chords for the slow "Yes Lord" song, or just play them slowly)
Eb / G-Bb-Eb (Yes Lord)
F / F-Ab-Eb
Gb / Gb-A-Eb
G / G-Bb-Eb (Yes)
Ab / Ab-C-Eb (Lord)
A / Gb-A-C-Eb (Yes Lord)
D / C-F-Ab
G / B-Eb-F-Bb
C / Bb-Eb-G
F / B-Eb-F-Ab (Yes)
Bb / Bb-Eb-G (Lord)
* / Ab-Bb-Eb-F (Yes Lord)
* / Ab-Bb-D-F
Eb / G-Bb-Eb (Yes Lord)
Gb / E-Bb-Eb
F / Eb-A-Eb
Bb / D-Ab-Eb
Eb / Db-G-C-Eb
You can try those and see what else you can come up with.